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mm: compaction: introduce isolate_freepages_range() 

This commit introduces isolate_freepages_range() function which
generalises isolate_freepages_block() so that it can be used on
arbitrary PFN ranges.

isolate_freepages_block() is left with only minor changes.

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Tested-by: Rob Clark <rob.clark@linaro.org>
Tested-by: Ohad Ben-Cohen <ohad@wizery.com>
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Robert Nelson <robertcnelson@gmail.com>
Tested-by: Barry Song <Baohua.Song@csr.com>
hifive-unleashed-5.1
Michal Nazarewicz 2012-01-30 13:24:03 +01:00 committed by Marek Szyprowski
parent 03d44192f6
commit 85aa125f00
1 changed files with 93 additions and 18 deletions
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111
mm/compaction.c
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@ -54,24 +54,20 @@ static unsigned long release_freepages(struct list_head *freelist)
return count;
}
/* Isolate free pages onto a private freelist. Must hold zone->lock */
static unsigned long isolate_freepages_block(struct zone *zone,
unsigned long blockpfn,
struct list_head *freelist)
/*
* Isolate free pages onto a private freelist. Caller must hold zone->lock.
* If @strict is true, will abort returning 0 on any invalid PFNs or non-free
* pages inside of the pageblock (even though it may still end up isolating
* some pages).
*/
static unsigned long isolate_freepages_block(unsigned long blockpfn,
unsigned long end_pfn,
struct list_head *freelist,
bool strict)
{
unsigned long zone_end_pfn, end_pfn;
int nr_scanned = 0, total_isolated = 0;
struct page *cursor;
/* Get the last PFN we should scan for free pages at */
zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
end_pfn = min(blockpfn + pageblock_nr_pages, zone_end_pfn);
/* Find the first usable PFN in the block to initialse page cursor */
for (; blockpfn < end_pfn; blockpfn++) {
if (pfn_valid_within(blockpfn))
break;
}
cursor = pfn_to_page(blockpfn);
/* Isolate free pages. This assumes the block is valid */
@ -79,15 +75,23 @@ static unsigned long isolate_freepages_block(struct zone *zone,
int isolated, i;
struct page *page = cursor;
if (!pfn_valid_within(blockpfn))
if (!pfn_valid_within(blockpfn)) {
if (strict)
return 0;
continue;
}
nr_scanned++;
if (!PageBuddy(page))
if (!PageBuddy(page)) {
if (strict)
return 0;
continue;
}
/* Found a free page, break it into order-0 pages */
isolated = split_free_page(page);
if (!isolated && strict)
return 0;
total_isolated += isolated;
for (i = 0; i < isolated; i++) {
list_add(&page->lru, freelist);
@ -105,6 +109,73 @@ static unsigned long isolate_freepages_block(struct zone *zone,
return total_isolated;
}
/**
* isolate_freepages_range() - isolate free pages.
* @start_pfn: The first PFN to start isolating.
* @end_pfn: The one-past-last PFN.
*
* Non-free pages, invalid PFNs, or zone boundaries within the
* [start_pfn, end_pfn) range are considered errors, cause function to
* undo its actions and return zero.
*
* Otherwise, function returns one-past-the-last PFN of isolated page
* (which may be greater then end_pfn if end fell in a middle of
* a free page).
*/
static unsigned long
isolate_freepages_range(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long isolated, pfn, block_end_pfn, flags;
struct zone *zone = NULL;
LIST_HEAD(freelist);
if (pfn_valid(start_pfn))
zone = page_zone(pfn_to_page(start_pfn));
for (pfn = start_pfn; pfn < end_pfn; pfn += isolated) {
if (!pfn_valid(pfn) || zone != page_zone(pfn_to_page(pfn)))
break;
/*
* On subsequent iterations ALIGN() is actually not needed,
* but we keep it that we not to complicate the code.
*/
block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
block_end_pfn = min(block_end_pfn, end_pfn);
spin_lock_irqsave(&zone->lock, flags);
isolated = isolate_freepages_block(pfn, block_end_pfn,
&freelist, true);
spin_unlock_irqrestore(&zone->lock, flags);
/*
* In strict mode, isolate_freepages_block() returns 0 if
* there are any holes in the block (ie. invalid PFNs or
* non-free pages).
*/
if (!isolated)
break;
/*
* If we managed to isolate pages, it is always (1 << n) *
* pageblock_nr_pages for some non-negative n. (Max order
* page may span two pageblocks).
*/
}
/* split_free_page does not map the pages */
map_pages(&freelist);
if (pfn < end_pfn) {
/* Loop terminated early, cleanup. */
release_freepages(&freelist);
return 0;
}
/* We don't use freelists for anything. */
return pfn;
}
/* Returns true if the page is within a block suitable for migration to */
static bool suitable_migration_target(struct page *page)
{
@ -145,7 +216,7 @@ static void isolate_freepages(struct zone *zone,
struct compact_control *cc)
{
struct page *page;
unsigned long high_pfn, low_pfn, pfn;
unsigned long high_pfn, low_pfn, pfn, zone_end_pfn, end_pfn;
unsigned long flags;
int nr_freepages = cc->nr_freepages;
struct list_head *freelist = &cc->freepages;
@ -165,6 +236,8 @@ static void isolate_freepages(struct zone *zone,
*/
high_pfn = min(low_pfn, pfn);
zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
/*
* Isolate free pages until enough are available to migrate the
* pages on cc->migratepages. We stop searching if the migrate
@ -201,7 +274,9 @@ static void isolate_freepages(struct zone *zone,
isolated = 0;
spin_lock_irqsave(&zone->lock, flags);
if (suitable_migration_target(page)) {
isolated = isolate_freepages_block(zone, pfn, freelist);
end_pfn = min(pfn + pageblock_nr_pages, zone_end_pfn);
isolated = isolate_freepages_block(pfn, end_pfn,
freelist, false);
nr_freepages += isolated;
}
spin_unlock_irqrestore(&zone->lock, flags);